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LWT-Food Science & Technology
Elsevier
LWT-Food Science & Technology

Elsevier

0023-6438

LWT-Food Science & Technology/Journal LWT-Food Science & Technology
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    Pulsed vacuum drying enhances drying of blueberry by altering micro-, ultrastructure and water status and distribution

    Liu, Zi-LiangXie, LongZielinska, MagdalenaPan, Zhongli...
    9页
    查看更多>>摘要：Effect of pulsed vacuum drying (PVD) on the drying kinetics, microstructure, ultrastructure, water distribution, and bioactive compounds of blueberries were investigated in the current work. Experiments showed that compared to hot air drying (HAD), the drying time of blueberries under PVD was shortened by 32.14% at the same drying temperature of 65 degrees C. Scanning electron microscopy (SEM) observations showed that several microcracks were formed on the surface of pulsed vacuum dried blueberries. The transmission electron microscopy (TEM) observations indicated that PVD resulted in the presence of abnormal cells of irregular shape and caused more serious damage to the cell walls of blueberries than HAD. Low field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) analyses showed that the successive changes between atmospheric pressure and vacuum resulted in the enlargement and interconnection of pores that are beneficial to the moisture transfer in the initial stage of drying. Compared to HAD, PVD had also a positive effect on maintaining higher contents of total phenolics (TP) and total monomeric anthocyanins (TMA). These findings clarified the mechanism that PVD enhances the drying efficiency and quality of dried blueberries.
      原文链接:
    • NSTL
    • Elsevier

    Oxidation of myofibrillar protein and crosslinking behavior during processing of traditional air-dried yak (Bos grunniens) meat in relation to digestibility

    Ma, JibingWang, XinyueLi, QiaoZhang, Li...
    8页
    查看更多>>摘要：In this study, the changes in the digestibility of myofibrillar protein were investigated during the processing of traditional air-dried yak meat to reveal the underlying mechanism of cascade induction among lipid oxidation, protein oxidation, and protein digestibility. The results show that, during the processing, its moisture content, water activity, lightness (L*), yellowness (b*), and springiness were dramatically reduced (P < 0.05), while its pH, hardness, cohesiveness, and chewiness increased significantly (P < 0.05); and its redness (a*) experienced an increase first and a decrease later (P < 0.05). With the extension of processing time, its lipid-oxidized products and protein carbonyl compounds significantly increased (P < 0.05), showing a significant correlation between them (P < 0.05). With the increase in protein oxidation, the a-helices was unfolded and transformed into beta-sheet and random coil (P < 0.05). Moreover, the disulfide bonds and dityrosine of the protein cross-linking products were significantly increased (P < 0.05). Therefore, the hydrolysis rate of protein by proteases was largely correlated with carbonyl, disulfide bonds, and dityrosine (P < 0.01). In conclusion, during the processing of air-dried yak meat, lipid-oxidized products appeared to have promoted protein oxidation. It was also found that the decrease in protein digestibility was caused by protein carbonylation and crosslinking, which affected the combination of pepsin and protein.
      原文链接:
    • NSTL
    • Elsevier

    Biotechnological production of D-tagatose from lactose using metabolically engineering Lactiplantibacillus plantarum

    Zhang, SusuGuo, TingtingXin, YongpingQin, Lihong...
    9页
    查看更多>>摘要：D-Tagatose is a low-calorie sweetener with health benefits. To produce D-tagatose from lactose, a metabolic engineering Lactiplantibacillus plantarum was constructed. The galactokinase gene galK was inactivated and the original promoter of beta-galactosidase gene lacLM was replaced by a strong lactose/galactose-inducible promoter PlacLM-35-10 in Lpb. plantarum WCFS1. Subsequently, the L-arabinose isomerase gene AraA derived from Lactobacillus casei SDMCC050286 was over-expressed. A recombinant strain with the potential of D-tagatose production was obtained. Its galactose metabolism pathway was blocked, and beta-galactosidase activity was increased by 5.4-folds. Meanwhile, the heterogeneous L-arabinose isomerase was highly expressed in this strain. The optimal conditions for D-tagatose production by resting cells of the recombinant strain were at 65 degrees C and pH 7.5. Furthermore, the conversion rate of D-tagatose from 175 g/L lactose reached 33% at 56 h. This study verified the feasibility of one-pot production of D-tagatose from lactose by engineering strain of Lpb. plantarum, thereby laying down the foundation for industrial usage of lactose.
      原文链接:
    • NSTL
    • Elsevier

    Improved photostability of folic acid by the radical-scavenging effect of tannic acid

    Cheng, YongqiangWang, YongquanYan, BingAbbaspourrad, Alireza...
    7页
    查看更多>>摘要：Folic acid (FA) is sensitive to ultraviolet (UV) light and decomposes into photoproducts with higher fluorescence quantum yield: 6-formylpterin (Fop) and p-aminobenzoylglutamic acid (PABA-Glu). Fop is subsequently oxidized into 6-carboxypterin (Cap). The increased fluorescence intensity of FA solution with increasing irradiation time proved the degradation. Addition of tannic acid (TA) at the TA/FA molar ratio of 0.025/1 could protect 99% FA compared to that no FA could be detected without addition of TA after 120 min of UV irradiation. The retention of FA without TA at pH 5-6 was below 0.4% and above 93% at pH 3-4, but the retention of FA with TA was over 97% for pH 3-6. Moreover, the retention of FA with TA in gummy was over 81% which was significantly higher than that of the one without TA. No covalent bonds were formed between TA and FA. Ethylenediaminetetraacetic acid could not protect FA against photodegradation. Ascorbic acid (Vc) could protect FA to the same extent as TA, but with more addition. It agreed with the results that the DPPH radical-scavenging effect of Vc is lower than TA. These results demonstrated that TA could improve the photostability of FA by the radical-scavenging effect.
      原文链接:
    • NSTL
    • Elsevier

    Infrared heating induced improvement of certain phytobioactives, their bioaccessible contents and bioaccessibility in maize

    Hossain, AshrafiJayadeep, A.
    8页
    查看更多>>摘要：The study investigated changes in nutraceuticals in infrared (IR) heated maize (140-200 degrees C), and their bioaccessible content, and bioaccessibility in the IR-140 sample (heated at 140 degrees C). The content of alpha-tocopherol (alpha-TP), alpha-tocotrienol (alpha-TT), and total phenolics remained unchanged at all treatments. The content of gamma-TP, zeaxanthin, beta-carotene, and phytosterols reduced at 160 degrees C and above temperature while gamma-TT, delta-TP, delta-TT, and lutein reduced in all the treated samples. The bioaccessible content of lutein and flavonoids increased in the IR-140 sample but zeaxanthin, beta-carotene, phytosterols, and total phenolics content did not change. Bioaccessibility of lutein, beta-carotene, and flavonoids increased, yet, bioaccessibility of phenolics and phytosterols was unchanged in the IR-140 sample. Bioaccessible content and bioaccessibility of tocopherols and tocotrienols reduced in the treated sample. Total antioxidant activity (TAA) of the bioaccessible fraction of the IR-140 sample increased while free radical scavenging (DPPH assay) activity and reducing power were similar to those of untreated maize. Bioaccessibility of TAA increased and bioaccessibility of radical scavenging activity and reducing power remained unchanged in the IR-140 sample although reducing power and TAA activity in IR-140 were lower in raw maize samples. Overall, IR heating of maize resulted in increase or retention of most of the phytobioactives and antioxidant activity, and their bioaccessible content and bioaccessibility.
      原文链接:
    • NSTL
    • Elsevier

    Effect of lactic acid bacteria and yeast fermentation on antimicrobial, antioxidative and metabolomic profile of naturally carbonated probiotic whey drink

    Kadyan, SaurabhRashmi, H. M.Pradhan, DiwasKumari, Anisha...
    10页
    查看更多>>摘要：The present study investigated the effect of lactic acid bacteria and yeast fermentation on development of a naturally carbonated probiotic whey drink using indigenous probiotic Lactobacillus plantarum MTCC 5690 and Kluyveromyces lactis NCDC 257. The CO2 level reached to 57.0 +/- 6.12 mL/40 mL whey with concomitant increase in headspace CO2 level from 2.2 to 68.7 percent after 24 h of incubation. The drink was shelf stable and organoleptically acceptable for a period of 21 days under refrigeration, with probiotic count of >= 10(8) cells/mL. The total phenolics, FRAP and DPPH activity of fermented drink was significantly higher (P < 0.05) than the unfermented whey. L. plantarum exhibited antagonistic activity against all pathogens via radial streak assay. However, cell free supernatant of drink exerted mostly K. lactis mediated antimicrobial activity with highest and lowest inhibition against E. coli (28.0 +/- 0.41 mm) and S. aureus (16.67 +/- 3.86 mm), respectively. Untargeted metabolomics profiling through gas chromatography mass spectrometry revealed 58 metabolites. Some of differential flavour and nutritional metabolites observed in co-cultured whey were propan-2-ol, hexanoic acid, ethyl propionate, erythritol etc. The developed whey drink is ready-to-serve (RTS) and can be easily incorporated by industrial stakeholders in their production lines, thereby minimizing effluent volume and treatment cost.
      原文链接:
    • NSTL
    • Elsevier

    Loop-mediated isothermal amplification (LAMP) for rapid detection of Salmonella in foods based on new molecular targets

    Shang, YutingYe, QinghuaCai, ShuzhenWu, Qingping...
    7页
    查看更多>>摘要：Various molecular techniques have been introduced for Salmonella detection. Loop-mediated isothermal amplification (LAMP) is a simple and easy-to-operate detection method compared with conventional PCR. However, the specificity and efficiency of DNA amplification relies on the selected target sequence. In this study, we aimed to identify new molecular targets and develop a LAMP-based method for the rapid detection of Salmonella in food samples. Using bioinformatics analysis and PCR verification, 3 and 10 molecular targets respectively unique to Salmonella genus and S. enterica were identified. The limit of detection (LOD) for these targets ranged from 2.1 x 10(2) to 2.1 x 10(3) CFU/mL. Of these, the ssaQ gene yielded 100% positive results upon testing with 23 most commonly reported Salmonella serovars and showed no cross-reaction with 22 non-Salmonella strains. Furthermore, its LOD was 2.1 x 10(1) CFU/mL, making it 10-fold more sensitive than the optimal PCR-based method. Therefore, the ssaQ gene was selected as the target gene to detect Salmonella using LAMP. The ability of the ssaQ-based LAMP method of detecting Salmonella in food samples was consistent with that of the standard culture method. The developed method has potential applications in identifying Salmonella contamination in food as well as for rapid and precise tracing of contamination sources in clinical diagnostics.
      原文链接:
    • NSTL
    • Elsevier

    Assembly of hyperhalophilic complex consortia of isolates from anchovy ripening attaining histamine degradation and their microbiome configuration

    Villegas-Plazas, MarcelaJunca, HowardMurialdo, Silvia E.Perez, Silvina...
    7页
    查看更多>>摘要：High histamine content in salted-ripened fish results in food safety detriment. The present study focused on the assembly of mixed cultures from halophilic prokaryotes isolated during salting-ripening anchovy process in order to determine their histamine-degrading capacity. For this purpose, 57 halophilic prokaryotes were inoculated together and submitted to several enrichment steps with strong shifts in culturing conditions and three microbial consortia were subsequently assembled: original consortium named C1 (without histamine exposure), consortium C2 (enriched in nutritive culture medium with high histamine content similar to 900 mg/kg) and consortium C3 (against histamine similar to 200 mg/kg) and reduced amounts of nutrients. These consortia were submitted to histamine-degrading capacity studies and 16S rRNA gene amplicons analysis. In the absence of histamine (C1), Salinivibro costicola (16.83%), Haloarcula spp. (11.08%) and Halococcus spp. (8.73%) were the most abundant. C2 presented ability to degrade histamine and major OTUs belonged to the family Halobacteriaceae and the genus Halomonas. C3 degraded histamine and predominant OTUs were from the family Halomonadaceae and the genus Chomohalobacter. Therefore, members of the archaeal family Halobacteriaceae and bacterial genera Halomonas and Chomohalobacter would be associated to histamine degradation and their potential as single or mixed starter cultures for improving salted-ripened foodstuff safety is promising.
      原文链接:
    • NSTL
    • Elsevier

    Identification and quantification of hydroxycinnamoylated catechins in tea by targeted UPLC-MS using synthesized standards and their potential use in discrimination of tea varieties

    Wang, WeiZhang, PengLiu, Xiao-HuanKe, Jia-Ping...
    9页
    查看更多>>摘要：The contents of hydroxycinnamoylated catechins (HCCs) in tea leaves have yet to be thoroughly investigated. Herein, four HCCs, (-)-epicatechin 3-O-p-coumaroate (EC-pC), (-)-epicatechin 3-O-caffeoate (EC-C), (-)-epigallocatechin 3-O-p-coumaroate (EGC-pC), and (-)-epigallocatechin 3-O-caffeoate (EGC-C) were synthesized as standards through an improved route and then identified in leaves of 40 and quantified in 20 tea cultivars using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). EC-C and EC-pC were synthesized for the first time. This study found that HCCs were widely present in the two varieties of tea, Camellia sinensis var. sinensis (CSS) and var. assamica (CSA). The contents of total four HCCs and EGC-pC were higher in CSS (729-1398 mg/kg for total HCCs, 483-1052 mg/kg for EGC-pC), while EC-C was higher in CSA (65-176 mg/kg) cultivars, suggesting that EC-C and EGC-pC could be used as biochemical markers to differentiate CSS from CSA tea cultivars. Changes in HCCs contents were detected from the tea leaves collected from April to October, indicating that tea leaves harvested in August would have the highest HCCs content.
      原文链接:
    • NSTL
    • Elsevier

    Study on the stability of intermediates in the process of enzymatic hydrolysis of phosphatidic acid by phospholipase A(1)

    Wang, TongCheng, JieZhang, XingzhenJiang, Lianzhou...
    7页
    查看更多>>摘要：In the degumming process of crude soybean oil by phospholipase A(1) (PLA(1)), the content of free fatty acids (FFA) in the product increases excessively. In this study, PLA(1) was used to hydrolyse simulated crude soybean oil. It was found that the acyl group at the sn-2 position migrated to the sn-1 position, the content of FFA in the oil was as high as 1.26 +/- 0.03 g/100 g, and the acyl migration rate was up to 38.9 +/- 0.10% after 2.8 h. Under the conditions of H3BO3 addition of 2 g/100 g, pH of 5, enzymatic hydrolysis temperature of 50 degrees C and enzymatic hydrolysis time of 2 h, the acyl migration rate of sn-2-HPA was 16.8 +/- 0.50%, the content of FFA was 1.14 +/- 0.02 g/100 g, and the enzymatic hydrolysis efficiency was increased by 28.57 +/- 0.07%.
      原文链接:
    • NSTL
    • Elsevier